diff --git a/include/boost/type_traits/is_union.hpp b/include/boost/type_traits/is_union.hpp
index 99f2dcf..89c4a0a 100644
--- a/include/boost/type_traits/is_union.hpp
+++ b/include/boost/type_traits/is_union.hpp
@@ -35,7 +35,7 @@ template <typename T> struct is_union_impl
 //
 template <typename T> struct is_union_impl
 {
-   BOOST_STATIC_CONSTANT(bool, value = BOOST_IS_UNION(cvt));
+   BOOST_STATIC_CONSTANT(bool, value = BOOST_IS_UNION(T));
 };
 #endif
 } // namespace detail